Refrigerator control thermostat



Sept. 6, 1949. c. w. KUHN REFRIGERATOR CONTROL THERMOSTAT Filed April 22, 1946 Patented Sept. 6, 1949 r I 2,480,987 REFRIGERATOR CONTROL TEERMOSTAT Clarence W. Kuhn, Wanwatosa, Wia, alsignor to Cutler-Hammer Inc., Milwaukee,

Meantime Wia. a cor- Application April 23, 19, Serial No. 683,835

This invention relates to refrigerator control switches.

The invention relates more particularly to switches of the dual temperature responsive type for effecting control of an electric refrigerator conjointly in response to temperature variations at different points therein.

The invention has among its objects to provid an improved dual temperature responsive control mechanism for refrigerator control switches which is exceedingl compact and rugged in construction, positive and reliable in operation, and which consists of a relatively small number of parts which can be readily manufactured and assembled at low cost.

.Another object is to provide a dual temperature responsive mechanism of the aforesaid character which can be readily applied to existing refrigerator control switches of various designs without substantial modification thereof and which comprises a unitary assembly including a pair of pressure responsive diaphragm elements of the wafer typ Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates an embodiment of the invention which will now be described, it being understood that various modifications may be made in the embodiment illustrated without departing from the spirit and scope of the appended claims.

In the drawing,

Figure 1 is a side elevational view of a refrigerator control device having a dual temperature responsive control assembly embodying the invention associated therewith;

Fig. 2 is a front view of the control device shown in Fig. l with the control assembly shown in section;

Fig. 8 is a sectional view on lines 3-! of Fig. 2;

Figs. 4 and 5 are exploded perspective views of certain of the parts of the control assembly shown in Figs. 1 and 2; and

Fig. 6 is a schematic view illustrating the switch mechanism employed in the device illustrated in Figs. 1 and 2 and also the control assembly therefor.

Referring to Figs. 1 and 2, a dual temperature responsive control assembly I embodying the invention is shown in connection with a refrigerator control device 2 of the type disclosed in the patent to C. F. Robbins, No. 2,375,387, issued May 8, 1945. The control device 2 is provided with a snap switch mechanism which is housed within an enclosing casing comprising a base plate I I Claims. (01. 2974) and a U-shaped cover member I, and as hereinafter set forth control assembly I is mounted upon said base plate and includes a. pair of temperature responsive elements 5 and 6 of the wafer type which operate coniointly to effect control of the snap switch mechanism against the action of a single loading spring I.

The snap switch mechanism associated with device 2 is schematically illustrated in Fig. 6 and briefly described this mechanism includes a normally closed switch 8 and a snap operating mechanism therefor including a pivoted operating lever 9, a pivoted control lever in and an over-center spring ll extending between said levers. Control lever III is normally held in engagement with a fixed stop I! under the action of spring H and with said control lever in normal position operating lever 9 is held by said spring in engagement with a stop II for closure of switch 8. Upon downward movement of control lever l0 away from its associated stop 12 the axis of spring Ii is shifted downwardly across the pivot 0f operating lever 9 and said spring then acts to move said operating lever downwardly with a snap action out of normal position for opening of switch 0. During return movement of control lever i0 toward stop I2 the axis of spring H is moved upwardly across the pivot of operating lever 9 and said spring then acts to effect snap movement of said operating lever into engagement with stop II for reclosure of switch 8. Switch 8 is carried by an insulating base M which is secured to one end of base plate 3 as illustrated in Fig. 1, and the snap operating mechanism for said switch is mounted upon the upper face of said base plate and is housed within the cover member 4.

The temperature responsive elements 5 and 8 of control assembly I are mounted upon the under side of base plate 3 and as shown in Fig. 2 each of said elements comprises a rigid cup member It of circular form having a flexible metal diaphragm it welded within the opening therein to provide a sealed chamber H. The cup member ii of element 5 is provided with a side tube extension II and the cup member ii of element 6 is provided with a center tube extension IS. The tube extensions l8 and iii are usually provided with sealed end portions and these tube extensions and their associated chambers I! are usually illled with a vaporizable fluid such as methyl chloride. Each of the cup members l5 has an outwardly extending securing flange 20 of rectangular shape formed on the open end thereof and said cup members are secured in spaced coaxial relation to the under side of base plate 8 by a frame 2| and four securing screws 22. The screws 22 extend through corner openings in the securin flanges 20 and thread into tapped openings in base plate 3.

Frame 2| is rectangular in shape and comprises two stamped and formed sheet metal sections 23 and 24 (Fig. 4) which are clamped between the under side of base plate 3 and the securing flange 20 of element 6 by the screws 22. Section 23 is provided with a side wall 25 having curved end corner portions 25 and 25", and section 24 is provided with a side wall 26 having curved end corner portions 26 and 25 The corner portions a and b of side walls 25 and 26 are each provided with a slot 21 and as shown in Figs. 1 and 3 the flange 20 of element is located between said side walls and supported at its corners within said slots. The sections 23 and 24 are also provided with end walls 28 and 29, respectively, which are clamped between the securing flanges 20 of elements 5 and 6 by the screws 22. Section 23 is also provided with a wall 30 which is located above the wall 29 of section and extends between the under side of base plate 3 and the flange 20 of element 5. As shown in Fig. 4, wall 29 of section 24 is provided with an opening 3| for receiving the tube extension l8 of element 5. Also as shown in .Fig. 4 each of the walls 28 and 29 has tongue projections 32 formed on the under edge thereof and these tongue projections engage within openings (not shown) in the securing flange 20 of element 6 to prevent lateral displacement of the frame sections 23 and 24.

The diaphragms E5 of elements 5 and'5 are operatively connected by cup members 34 and 35 to provide for control of switch 8 conjointly by said elements against the action of loading spring 1. Cup members 34 and 35 comprise sheet metal stampings and as shown in Fig. 5 cup member 34 has horizontally disposed projections 35-36 formed on opposite sides thereof, each of which is notched as shown at 31, and cup member 35 has vertically disposed arms 38--38 formed on opposite sides thereof, each of which is provided with a T-shaped end portion 33. Cup members 34 and 35 are secured together by engagement of the end portions 39 on arms 38 within the notches 37 in projections 36, and as shown in Figs. 2 and 3, thearms 38 of cup member 35 are disposed on opposite sides of element 5 within spaces provided between said element and the side walls 25 and 26 of frame 2!.

As shown in Fig. 2, the lower end of loading spring 1' has a washer 40 associated therewith which is supported upon a spacer 48 mounted upon the upper side of cup member 34. Also asschematically illustrated in Fig. 6, the lower end of loading spring 1 is operatively connected to control lever H! to efiect downward movement of said lever against the action of its associated overcenter spring ll. Loading spring l is adjustable by a rotatable knob 42 which is carried by a plate 43"mounted upon the front end of cover 4, as shown in Fig. 1. Knob 42 is provided with a cam adjusting portion 44 (Fig. 6) which is operatively connected to spring I through the medium of a cam follower 45 and a pivoted lever 46.

The aforedescribed control device may be used to effect control of an electric refrigerator in response to temperature conditions at different points therein. Thus tube I8 of temperature responsive device 5 may be attached to the evaporator plate of the refrigerator and tube I9 of temperature responsive device 6 may be located within the food compartment of the refrigerator in contact with an outer wall thereof. As is apparent, element 5 then operates to effect closure and opening of switch 8 for starting and stopping of the refrigerator at temperature values within the evaporator which are determined by the setting of loading spring I and the pressure exerted by element 8 in opposition to said spring. Thus assuming that the temperature of the outer wall, of the food compartment of the refrigerator increases due to an increase in room temperature, the pressure exerted by element 6 increases to reduce the loading effect of spring 'I on element 5 and thereby provides for operation of switch 8 by element 5 at lower evaporator temperatures. 0n the other hand, assuming that the temperature of the outer wall of the food compartment of the refrigerator decreases due to a drop in room temperature, the pressure exerted by element 6 increases so that switch 8 is operated by element 5 at higher evaporator temperatures. Switch 8 is thus controlled by element 5 to normally maintain the evaporator at a predetermined mean temperature determined by the setting of loading spring I, and element 6 acts as a modifying means to vary the temperature of the evaporator in such a manner as to maintain a substantially uni form temperature within the food compartmen regardless of changes in room temperature.

What I claim as new and desire to secure by Letters Patent is:

1. In a dual temperature responsive operating assembly for outside mounting upon an encased refrigerator control device or the like, the combination with a pair of temperature responsive elements of the wafer type each including a, rigid cup member having an outwardly extending supporting flange, and each including an expansible diaphragm sealed within said cup member. of securing means associated with the flanges of said cup members for attaching said wafer elements in axially aligned relation to the casing of said control device and in spaced relation one to another, said securing means comprising a hollow shell forming a spacer between said cup members and forming with said encased device and one of said cup members an enclosure for the assembly.

2. In a dual temperature responsive operating assembly for outside mounting upon an encased refrigerator control device or the like, the combination with a pair of temperature responsive elements of the wafer type each including a rigid cup member having an outwardly extending supporting flange and each including an expansible diaphragm sealed within said cup member, of securing means associated with the flanges of said cup members for attaching said wafer elements in spaced coaxial relation to the casing of said control device, said securing means comprising a hollow shell forming a spacer between said cup members and forming with said encased device and one of said cup members an enclosure for the assembly and a yoke member located within said shell and engaging the diaphragms of both of said wafer elements to efiect control of said device conjointing by said wafer elements.

3. In a dual temperature responsive operating assembly for outside mounting upon an encased refrigerator control or the like, the combination with a pair of temperature responsive elements of the wafer type each including a rigid cup member having an outwardly extending supporting flange and each including an expansible diaphragm sealed within said cup member, of securing means associated with the flanges of said cup members for attaching said wafer element in spaced coaxial relation to the casing of said control device, said securing means comprising a hollow shell forming a spacer between said cup members and forming with said encased device and one of said cup members an enclosure for said assembly, and a plurality of securing screws extending through aligned openings in the flanges of said cup members for securing said wafer elements and said shell in assembled position upon said encased device.

4. In a dual temperature responsive operating assembly for outside mounting upon an encased refrigerator control device or the like, the combination with a pair of temperature responsive elements of the wafer type each including a rigid cup member having an outwardly extending supporting flange and each including an expansible diaphragm sealed within said cun member, of

securing means associated with the flanges of said cup members for attaching said water elements in spaced coaxial relation to the casing of said control device, said securing means including a hollow shell consisting of two sheet metal parts forming a spacer between said cup members and forming with said encased device and one of said cup members an enclosure for the assembly, and a plurality of securing screws extending through aligned openings in the flanges of said cup members to hold said water elements and the parts of said shell in assembled position upon the easing of said control device.

CLARENCE W. KUHN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 672,965 Shaw Apr. 30, 1901 1,899,516 Mabey Feb. 28, 1933 2,048,620 Pervelis July 21, 1936 2,210,035 Kuhn Aug. 6, 1940 2,345,505 Seidle Mar. 28, 1944 

